<s>
In	O
computer	O
graphics	O
,	O
planar	B-Device
is	O
the	O
method	O
of	O
arranging	O
pixel	B-Algorithm
data	O
into	O
several	O
bitplanes	O
of	O
RAM	B-Architecture
.	O
</s>
<s>
Each	O
bit	O
in	O
a	O
bitplane	O
is	O
related	O
to	O
one	O
pixel	B-Algorithm
on	O
the	O
screen	O
.	O
</s>
<s>
Unlike	O
packed	B-General_Concept
,	O
high	O
color	O
,	O
or	O
true	O
color	O
graphics	O
,	O
the	O
whole	O
dataset	O
for	O
an	O
individual	O
pixel	B-Algorithm
is	O
n't	O
in	O
one	O
specific	O
location	O
in	O
RAM	B-Architecture
,	O
but	O
spread	O
across	O
the	O
bitplanes	O
that	O
make	O
up	O
the	O
display	O
.	O
</s>
<s>
Planar	B-Device
arrangement	O
determines	O
how	O
pixel	B-Algorithm
data	O
is	O
laid	O
out	O
in	O
memory	O
,	O
not	O
how	O
the	O
data	O
for	O
a	O
pixel	B-Algorithm
is	O
interpreted	O
;	O
pixel	B-Algorithm
data	O
in	O
a	O
planar	B-Device
arrangement	O
could	O
encode	O
either	O
indexed	B-Data_Structure
or	O
direct	O
color	O
.	O
</s>
<s>
The	O
memory	O
chips	O
of	O
this	O
era	O
can	O
not	O
supply	O
data	O
fast	O
enough	O
on	O
their	O
own	O
to	O
generate	O
a	O
picture	O
on	O
a	O
TV	O
screen	O
or	O
monitor	O
from	O
a	O
large	O
framebuffer	B-Algorithm
.	O
</s>
<s>
These	O
chips	O
can	O
then	O
be	O
read	O
in	O
parallel	O
at	O
a	O
slower	O
rate	O
,	O
allowing	O
graphical	O
display	O
on	O
modest	O
hardware	O
,	O
like	O
game	O
consoles	O
of	O
the	O
third	B-Application
and	O
fourth	B-Application
generations	O
and	O
home	O
computers	O
of	O
the	O
80s	O
.	O
</s>
<s>
The	O
EGA	B-Device
video	O
adapter	O
on	O
early	O
IBM	B-Device
PC	I-Device
computers	O
uses	O
planar	B-Device
arrangement	O
in	O
color	O
graphical	O
modes	O
for	O
this	O
reason	O
.	O
</s>
<s>
The	O
later	O
VGA	B-Protocol
includes	O
one	O
non-planar	O
mode	O
which	O
sacrifices	O
memory	O
efficiency	O
for	O
more	O
convenient	O
access	O
.	O
</s>
<s>
Game	O
consoles	O
with	O
a	O
planar	B-Device
display	O
organization	O
include	O
Sega´s	O
Master	O
System	O
and	O
Game	O
Gear	O
,	O
Nintendo´s	O
NES	O
/	O
SNES	B-Application
,	O
and	O
the	O
PC	B-General_Concept
Engine	I-General_Concept
.	O
</s>
<s>
The	O
British	O
8-bit	O
BBC	B-Device
Micro	I-Device
has	O
partial	O
elements	O
of	O
a	O
planar	B-Device
pixel	B-Algorithm
arrangement	O
.	O
</s>
<s>
The	O
Slovak	O
PP	O
01	O
includes	O
a	O
24KB	O
plane-based	O
8-colour	O
graphics	O
mode	O
with	O
a	O
resolution	O
of	O
256x256	O
pixels	B-Algorithm
.	O
</s>
<s>
The	O
16-bit	O
Atari	B-Device
ST	I-Device
and	O
Amiga	B-Device
platforms	I-Device
from	O
the	O
80s	O
and	O
90s	O
were	O
exclusively	O
based	O
on	O
a	O
planar	B-Device
graphics	O
configuration	O
along	O
side	O
a	O
powerful	O
blitter	B-General_Concept
.	O
</s>
<s>
Amiga´s	O
OCS	O
graphics	O
chipset	O
works	O
with	O
5	O
bitplanes	O
while	O
later	O
models	O
with	O
the	O
AGA	O
chipset	O
can	O
handle	O
eight	O
bitplanes	O
.	O
</s>
<s>
For	O
the	O
Sinclair	O
(	O
Amstrad	O
)	O
ZX	B-Operating_System
Spectrum	I-Operating_System
computer	O
family	O
and	O
compatible	O
systems	O
,	O
a	O
graphics	O
expansion	O
named	O
HGFX	O
was	O
developed	O
in	O
2019	O
.	O
</s>
<s>
In	O
2022	O
it	O
was	O
implemented	O
in	O
FPGA-based	O
hardware	O
.	O
</s>
<s>
The	O
HGFX	O
enables	O
a	O
memory	O
organization	O
that	O
is	O
compatible	O
with	O
the	O
original	O
ZX	B-Operating_System
Spectrum	I-Operating_System
system	O
while	O
taking	O
up	O
only	O
6144	O
bytes	O
of	O
the	O
original	O
video	O
RAM	B-Architecture
.	O
</s>
<s>
In	O
addition	O
,	O
it	O
provides	O
two	O
video-buffers	O
,	O
256	O
indexed	B-Data_Structure
colours	I-Data_Structure
,	O
a	O
truecolour	O
palette	O
,	O
and	O
an	O
HDMI	O
output	O
.	O
</s>
<s>
On	O
a	O
chunky	B-General_Concept
display	O
with	O
4-bits-per-pixel	O
and	O
a	O
RGBI	O
palette	O
,	O
each	O
byte	O
represents	O
two	O
pixels	B-Algorithm
,	O
with	O
16	O
different	O
colors	O
available	O
for	O
each	O
pixel	B-Algorithm
.	O
</s>
<s>
Four	O
consecutive	O
pixels	B-Algorithm
are	O
stored	O
in	O
two	O
consecutive	O
bytes	O
as	O
follows	O
:	O
</s>
<s>
Whereas	O
a	O
planar	B-Device
scheme	O
could	O
use	O
2	O
bitplanes	O
,	O
providing	O
for	O
a	O
4	O
color	O
display	O
.	O
</s>
<s>
Eight	O
pixels	B-Algorithm
would	O
be	O
stored	O
as	O
2	O
bytes	O
non-contiguously	O
in	O
memory	O
:	O
</s>
<s>
In	O
the	O
planar	B-Device
example	O
,	O
2	O
bytes	O
represent	O
8	O
pixels	B-Algorithm
with	O
4	O
available	O
colors	O
,	O
where	O
the	O
packed	B-General_Concept
pixel	I-General_Concept
example	O
uses	O
2	O
bytes	O
to	O
represent	O
fewer	O
pixels	B-Algorithm
but	O
with	O
more	O
colors	O
.	O
</s>
<s>
For	O
example	O
,	O
using	O
4	O
planes	O
makes	O
24	O
=	O
16	O
colors	O
available	O
,	O
but	O
it	O
would	O
then	O
take	O
4	O
bytes	O
to	O
represent	O
8	O
pixels	B-Algorithm
(	O
making	O
it	O
equivalent	O
in	O
terms	O
of	O
memory	O
usage	O
and	O
available	O
colors	O
to	O
the	O
packed	B-General_Concept
arrangement	O
example	O
)	O
.	O
</s>
<s>
Planar	B-Device
arrangements	O
offer	O
space	O
and	O
time	O
efficiencies	O
over	O
packed	B-General_Concept
arrangements	O
at	O
bit	O
depths	O
that	O
are	O
n't	O
powers	O
of	O
2	O
.	O
</s>
<s>
With	O
planar	B-Device
arrangements	O
,	O
this	O
simply	O
requires	O
3	O
planes	O
.	O
</s>
<s>
With	O
packed	B-General_Concept
arrangements	O
,	O
supporting	O
exactly	O
3	O
bpp	O
would	O
require	O
either	O
allowing	O
pixels	B-Algorithm
to	O
cross	O
byte	O
boundaries	O
(	O
incurring	O
time	O
costs	O
due	O
to	O
complications	O
with	O
addressing	O
and	O
unpacking	O
pixels	B-Algorithm
)	O
or	O
padding	O
(	O
incurring	O
space	O
costs	O
,	O
as	O
each	O
byte	O
would	O
store	O
2	O
pixels	B-Algorithm
and	O
have	O
2	O
unused	O
bits	O
)	O
;	O
historically	O
,	O
this	O
is	O
one	O
reason	O
(	O
though	O
not	O
necessarily	O
the	O
main	O
one	O
)	O
packed	B-General_Concept
pixels	I-General_Concept
used	O
bit	O
depths	O
that	O
fit	O
evenly	O
into	O
bytes	O
.	O
</s>
<s>
Planar	B-Device
arrangements	O
allow	O
for	O
faster	O
bit	O
depth	O
switching	O
:	O
planes	O
are	O
added	O
or	O
discarded	O
and	O
(	O
if	O
colors	O
are	O
indexed	B-Data_Structure
)	O
the	O
palette	O
is	O
extended	O
or	O
truncated	O
.	O
</s>
<s>
A	O
disadvantage	O
of	O
planar	B-Device
arrangements	O
is	O
that	O
more	O
RAM	B-Architecture
address	O
cycles	O
are	O
needed	O
for	O
scrolling	O
and	O
animations	O
.	O
</s>
